AT91SAM9261S_1 Datasheet, PDF (417/709 Pages) ATMEL Corporation – AT91 ARM Thumb-based Microcontrollers

AT91SAM9261S
32.6.5.1
• Configure the TXD pin as PIO and set it as an output at 0 (to avoid LED emission). Disable
the internal pull-up (better for power consumption).
• Receive data
IrDA Modulation
For baud rates up to and including 115.2 Kbits/sec, the RZI modulation scheme is used. “0” is
represented by a light pulse of 3/16th of a bit time. Some examples of signal pulse duration are
shown in Table 32-9.
Table 32-9.
Baud Rate
2.4 Kb/s
9.6 Kb/s
19.2 Kb/s
38.4 Kb/s
57.6 Kb/s
115.2 Kb/s
IrDA Pulse Duration
Pulse Duration (3/16)
78.13 µs
19.53 µs
9.77 µs
4.88 µs
3.26 µs
1.63 µs
Figure 32-24 shows an example of character transmission.
Figure 32-24. IrDA Modulation
Transmitter
Output
Start
Bit
0 10
Data Bits
1 ⁰⁰¹¹
Stop
Bit
01
TXD
32.6.5.2
Bit Period
3
16
Bit
Period
IrDA Baud Rate
Table 32-10 gives some examples of CD values, baud rate error and pulse duration. Note that
the requirement on the maximum acceptable error of ±1.87% must be met.
Table 32-10. IrDA Baud Rate Error
Peripheral Clock
Baud Rate
CD
Baud Rate Error
Pulse Time
3 686 400
115 200
2
0.00%
1.63
20 000 000
115 200
11
1.38%
1.63
32 768 000
115 200
18
1.25%
1.63
40 000 000
115 200
22
1.38%
1.63
3 686 400
57 600
4
0.00%
3.26
20 000 000
57 600
22
1.38%
3.26
32 768 000
57 600
36
1.25%
3.26
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